Treatment of oil for removal of alkali metal salts



10, 1954 J. c. SHOWALTER 2,686,149

TREATMENT OF OIL FOR REMOVAL OF ALKALI METAL SALTS Filed Dec. 28, 1950HYDROGARB ON CONTAINING ALKALI METAL SALTS N INGORPORATOR 3 Lpnomus nrsnI9 N I HEATER nouns h 1 s -2i ii"!!! --sv4rbn4ron 23 sur use on.

mu usnu. snrs INVENTOR. Jere C. Showalfen,

A6 NT Patented Aug. 10, 1954 TREATMENT OF OIL FOR REMOVAL OF ALKALIMETAL SALTS Jere C. Showalter, Baytown, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation of Delaware Application December 28, 1950, Serial No.203,124

9 Claims. 1

The present invention is directed to a method for treating a hydrocarboncontaining alkali metal salts to recover therefrom a substantiallysalt-free oil. In its more particular aspects, the invention has to dowith the removal of alkali metal naphthenates and/or alkali metalsulfonates from hydrocarbons containing them to allow recovery of thenaphthenates and sulfo mates and to produce a substantially salt-freeoil.

The present invention may be briefly described as involving theformation of a mixture of a by drocarbon oil containing alkali metalsalts with at least 10% by volume of water, following which thewater-containing admixture is agitated vigorously to form an emulsion.The emulsion is then extracted with liquefied propane at a temperaturein the range between 100 and 200 F. to form at least an oil phase and anaqueous phase. The propane may be removed from the oil phase to allowrecovery of a substantially salt-free oil which may suitably be used asa feed stock for catalytic cracking operations, while the aqueous phasemay have water removed therefrom to allow recovery of the alkali metalsalt. When the alkali metal salt is an alkali metal sulfonate, thesulfonates may be recovered in improved yields and purity.

The feed stocks to the process of the present invention may suitably besulfuric acid treated mineral oils, such as those used in the productionof white oils. For example, these oils are exhaustively treated withstrong sulfuric acid and then neutralized with an alkali metalhydroxide, such as sodium hydroxide. The neutralized oil may then formthe feed stock for the present invention. Other acid treated andneutralized oils containing alkali metal sulfonates may also be employedin the practice of the present invention.

The invention is not restricted, however, .to such feed stocks and maybe suitably used in removing alkali metal salts from neutralized sludgesresulting from the treatment in propane solutions of lubricating oilfractions with sulfuric acid. The oils resulting from the distillationof crude oil and crude petroleum fractions, such as lubricating oilfractions, over alkali metal hydroxides which contain substantial.quantitles of alkali metal naphthenates are also suitable as feed stockto my process. Neutralized slop oils containing alkali metal sulfonates,such as sodium sulfonates, and alkali metal naphthenates may also betreated in accordance with the practice of the present invention toallow recovery of a substantially salt-free oil.

In practicing the present invention, it is essential that the watercontent of the oil containing either sulfonates and/or naphthenates haveits water content adjusted so that the water content is at least 10% byVolume. If the water content is not adjusted, the salt content may bereduced but not lowered to the extent where substantially all of thevaluable sulfonates are recovered or where substantially all of thesalts are removed from the oil. If substantially all of the sulfonatesare not removed from the oil, valuable materials are lost and the oil isdegraded in quality. If substantially all of the salts, such asnaphthenates and sulfonates, are not removed from the oil, the oil islargely unsuitable either as a fuel oil or as a cracking stock.

The present invention will be further 'L lustrated by reference to thedrawing in which the single figure represents a flow diagram of apreferred mode of practicing the invention. In the drawing numeral lldesignates a charge tank containing a hydrocarbon, such as a lubricatingoil fraction, which has been treated with strong sulfuric acid for whiteoil manufacture and which contains an alkali metal sulfonate, such assodium sulfo-nate. The oil containing sodium. sulfonates in tank H iswithdrawn therefrom by line l2 to which is added by line I3 at least 10%by volume of water. The admixture of oil and water in line 12 is thendischarged into an incorporator I l or other suitable mixing device,such as a centrifugal pump, a tank containing an agitator, and the likeor other suitable mixing means wherein the admixture of oil and watercontaining alkali metal sulfonates is formed into an emulsion. Theemulsified admixture is then withdrawn by line [5 and has added to it asuitable amount of pro-pane which is introduced by line It. The amountof propane employed will vary from about 2 volumes of propane per volumeof oil up to about 10 volumes of propane per volume of oil. A suitableamount is approximately 6 volumes. The emulsion to which propane hasbeen added in line l5 then passes through a heater ll wherein thetemperature is raised to a temperature in the range between and 200 F. Atemperature of F. gives entirely satisfactory results in separatingsodium sulfonates. The propane, of course, is maintained in a liqueficdcondition by application of suitable pressures. The heated mixture ofpropane and emulsifled oil is then discharged by line l5 into aseparator vessel IS. The propane acts as a solvent and preferentiallydissolves the hydrocarbon while the sodium sulfonates are dissolvedsubstantially in the aqueous phase in separator 18 which is of suficientcapacity to allow a residence time for separation by gravity of theadmixture into at least an oil phase and an aqueous phase. For thepurpose of this description wherein oil which has been treated for whiteoil manufacture and which contains sodium sulfonates is extracted withpropane, an oil phase and an aqueous phase obtains. The oil phase iswithdrawn from separator 18 by line it and dis charged thereby into a.distillation tower or other suitable separation means 20 to allowremoval of propane from the oil. Conditions in distillation tower 20 areadjusted by heating means illustrated by steam coil 2! whereby propaneis removed from the oil and discharged from tower 20 by line 22. Asubstantially saltfree oil is recovered from tower 20 by line 23 whichmay be used for further treatment with sulfuric acid. for white oilmanufacture or may be recovered for use as a white oil it the oil hasbeen exhaustively treated prior to treatment in accordance with thepresent invention.

The aqueous phase separated in separator i8 is withdrawn therefrom byline 2@ controlled by valve 25 and discharged thereby into an evaporator26 which is a conventional type evaporator or evaporators and allowsremoval of water by line 2'5. The alkali metal salts, such as sodi umsulfonate, may be discharged from evaporator 26 by line 28.

When the oil in tank I i is a neutralized sludge resulting from thetreatment in propane solution of lubricating oil fractions with sulfuricacid or a neutralized slop oil or a hydrocarbon fraction resulting fromthe distillation of a crude 3| controlled by valve 32, valve in line 2 4being in a closed position, provided the amount of sulfonates and/ornaphthenates in the aqueous phase is insufficient for economicalrecovery.

The invention will be further illustrated by reference to the followingexamples:

EXAMPLE I In this example in accordance with the present invention a 500Vis. 100 F. Coastal lubrieating oil distillate was heated to 145 F. andthen 7.8 volume per cent of oleum was applied. The sludge was drawn andthe acid oil was blown with air to expel the sulfur dioxide and causethe pepper sludge to coagulate. The acid oil was then neutralized withaqueous sodium hydroxide, and the neutralized oil was emulsified with 10volume per cent of water. The sulfonates were extracted from thismixture with 6 volumes of liquid propane at 150 F, These steps wererepeated four times. After the fourth acid dump it was observed that theyield of sulfonates was so low that another acid application would notbe profitable. Therefore, the oil was finished for white oil. After thefourth propane extraction, the oil still contained approximately 1.5weight per cent of sulfonates. Since these sulfonates could not bewashed from the oil with hot water alone, 10 volume per cent of 92%isopropyl alcohol was used along with the water. After this extractionthe oil was steamed and dried and then percolated through to meshAttapulgus clay to produce USP white oil. The quantity of materials usedfor each treat, and the yields obtained are given in the followingtable:

Table I EXTRAOTING SUFONATES WITH PROPANE Propane i Oil Chg. Water CrudeS111 y Oll Oleum 011 Re- Sludge Re- Free Vi atei Extracted figi ggCharged Applied, covered, covered, gg g gggi gg ggggi Recovered, Oil RigTreat, cc. Treat, cc. Grams 20, 000 l, 560 16, 600 4, 911 16, 600 I, 660696 137 15, 000 16, 000 l, 560 12, 800 4, 713 12, 800 l, 280 l, 809 23410,000 10, 000 l, 560 9, 000 2, 560 9, 506 950 l, 087 332 2, 000 4.. 9,000 1 560 7, 640 2, 920 7, 640 764 115 480 I. 500

1 Contains sulfuric acid. 1 Contains 115 grams dry sulfonates.

oil or a fraction thereof over an alkali metal EXAMPLE II hydroxide, theamount of water employed is about 25% by volume. When such latter feedstocks are used, it may be desirable also to wash the oil-propanemixture after heating to a temperature in the range between 100 to 200F. with further quantities of water. Also, when such feed stocks areemployed, there is formed in separator it three phases rather than twophases. There is formed the oil phase, an intermediate phase, and anaqueous phase. The oil phase contains propane having the oil insolution. The intermediate phase contains substantially all of the saltsor ashy materials and also asphaltic bodies, if present, while theaqueous phase may contain sodium sulfonates and/or naphthenates over andbeyond that present in the intermediate phase. When such fractions formthe feed stocks of the process of the present invention, theintermediate phase may be discharged from separator 18 by line 29controlled by valve 30 while the aqueous phase may be discharged fromthe system by line 24 and line In order to illustrate the improvement ofthe present invention over the prior art processes a 500 Vis. F. Coastallubricating oil distillate was treated with 3 successive '7 .8 volumeper cent applications of oleum at F. The acid oil was air blown to expelthe sulfur dioxide and coagulate the pepper slude. This acid oil wasthen neutralized with aqueous sodium hydroxide and the sulfonatesextracted with one-half a volume of 50% isopropyl alcohol. The extractedoil was heated and blown with air to expel all water and traces ofalcohol. The remaining oil was treated with two more applications of 7.8volume per cent of oleum and then the sulfonates were extracted withpropane as before. The residue oil was finished for white oil. v

A comparative analysis of the sulfonates obtained by these two processesis ven i t e following Table II, and a comparison of the sulfonate yieldobtained by the two processes is given inTab1eIII."'

Table II ANALYSIS or CRUDE SULFONATES traction After Each 3d Acid Dump%;3?

Based on Oil Chgd., Lb./Bbl 32.;

11. Based on Oil Chgd., Wt. Percent .l 3.

It will be seen from the foregoing comparisons that the practice of thepresent invention allows the production of sulfonates containing lesserquantities of oil than the conventional alcohol extraction process.Furthermore, the practice of the present invention allows the obtainingof substantially greater quantities of sulfonates than the prior artprocesses.

In other operations in accordance with the present invention neutralizedpropane lube plant sludge resulting from the neutralization of sludgeproduced by sulfuric acid treating in propane solution of a lubricatingoil fraction, a neutralized separator slop oil, and a blend ofneutralized bottoms fractions from the distillation of naphtha,neutralized propane lube plant sludge, oil resulting from thedistillation of a petroleum fraction over caustic, and a neutralizedslop oil were treated by adjusting the water content to about 25%,following which the mixture was agitated to emulsify same and thenadmixed with 4 vols. of liquid propane at 150 F. to cause an extractionthereof. In the final separation stage a low ash content oil stream, anashy residual material, and a water phase were recovered. The oil streamwas then depropanized and tested. When the feed stock was theneutralized propane lube plant sludge, the content of salt or ash bodieswas reduced by treatment in accordance with the practice or the presentinvention from 7,200 p. p. m. to 38 p. p. m. The neutralized separatorslop oil was treated similarly and the ash or salt content was reducedfrom 30,000 p. p. m. to 60 p. p. m. The blend had an ash content of13,880 p. p. In prior to treatment in accordance with the presentinvention. After treatment, the ash content of it was 43 p. p. m.

It will be seen from the foregoing examples that the present inventionallows the recovery of high yields of high purity sulfonates. Theprocess is adaptable to the recovery of naphthenates as well. It willalso be obvious that the present invention allows the production of lowash or salt content oils which may be used as cracking stocks incatalytic cracking, or the oils having low ash content may suitably beused as fuel oils. It is well known that salts are deleterious in fueloils because of the tendency of the salts to form slags in furnaces andalso to clog burner openings.

The nature and objects of the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent is:

1. A process for treating a hydrocarbon oil mixture selected from thegroup consisting of neutralized slop oils, neutralized sludges resultingfrom treatment of lubricating oil fractions in propane solution withsulfuric acid, neutralized bottoms fractions from the distillation ofnaphtha, oil resulting from the distillation of crude petroleum and itsfractions over caustic, and neutralized acid oils resulting fromtreatment oflubricating oil with sulfuric acid containing an alkalimetal salt of an organic acid selected from the group consisting ofnaphthenic and sulfonic acids which comprises forming with said mixturea second mixture containing about 25% by volume of water, agitatingvigorously said water-containing admixture to emulsify same, extractingthe emulsified admixture with pro pane in an amount in the range fromabout 2 volumes to about 10 volumes per volume of hydrocarbon oil at'atemperature in the range between and 200 F. to form at least an oilphase substantially free of alkali metal salts and an aqueous phase,separating said phases, removing propane from said oil phase andrecovering an oil substantially free of salt of said organic acid.

2. A process in accordance with claim 1 in which the alkali metal saltis a salt of naphthenic acid.

3. A process in accordance with claim 1 in which the alkali metal saltis a salt of sulfonic acid.

4. A process for producing a hydrocarbon substantially free of salt ofan organic acid which comprises forming a mixture of a hydrocarbon oilselected from the group consisting of neutralized slop oils, neutralizedsludges resulting from treatment of lubricating oil fractions in propanesolution with sulfuric acid, neutralized bottoms fractions from thedistillation of naphtha, oil resulting from the distillation of crudepetroleum and its fractions over caustic, and neutralized acid oilsresulting from treatment of lubricating oil with sulfuric acidcontaining an alkali metal salt of an organic acid selected from thegroup consisting of naphthenic and sulfonic acids and about 25% byvolume of water, agitating vigorously said water-containing admixture toemulsify same, extracting the emulsified admixture with liquefiedpropane in an amount in the range from about 2 volumes to about 10volumes per volume of hydrocarbon oil at a temperature in the rangebetween 100 and 200 F. to form an oil phase, an intermediate phase andan aqueous phase, separating and recovering said oil phase and saidaqueous phase, removing pro pane from said oil phase and recovering anoil substantially free of salt of said organic acid.

5. A process for producing a hydrocarbon substantially free of salts oforganic acid which comprises forming a mixture of a hydrocarbon oilselected from the group consisting of neutralized slop oils, neutralizedsludges resulting from treat ment of lubricating oil fractions inpropane solution with sulfuric acid, neutralized bottoms fractions fromthe distillation of naphtha, oil resulting from the distillation ofcrude petroleum and its fractions over caustic, and neutralized acidoils resulting from treatment of lubricating oil with sulfuric acidcontaining sodium naphthenate and about 25% by volume of water,agitating vigorously said water-containing admixture to emulsify same,extracting the emulsified admixture with liquefied propane in an amountin the range from 2 volumes to about 10 volumes per volume ofhydrocarbon oil at a temperature in the range between 100 and 200 F. toform an oil phase, an intermediate phase and an aqueous phase,separating and recovering said oil phase and said aqueous phase,removing propane from said oil phase and recovering a substantiallysodium naphthenate-free oil.

6. A process for producing a hydrocarbon substantially free of salts oforganic acid which cornprises forming a mixture of a hydrocarbon oilselected from the group consisting of neutralized slop oils, neutralizedsludges resulting from treatment of lubricating oil fractions in propanesolution with sulfuric acid, neutralized bottoms frac tions from thedistillation of naphtha, oil resulting from the distillation of crudepetroleum and its fractions over caustic, and neutralized acid oilsresulting from treatment of lubricating oil with sulfuric acidcontaining sodium sulfonate and about 25% by volume of water, agitatingvigorously said water-containing admixture to emulsify same, extractingthe emulsified admixture with liquefied propane in an amount in therange from about 2 volumes to about volumes per volume of hydrocarbonoil at a temperature in the range between 100 and 200 F. to form an oilphase, an intermediate phase and an aqueous phase, separating andrecovering said oil phase and said aqueous phase, removing propane fromsaid oil phase and recovering a substantially sodium sulfonate-free oil.

7. A process for producing a hydrocarbon substantially free of salt ofan organic acid hydrocarbon which comprises forrning a mixture of ahydrocarbon oil selected from the group consisting of neutralized stopoils, neutralized sludges resulting from treatment of lubricating oilfractions in propane solution with sulfuric acid, neutralized bottomsfractions from the distillation of naphtha, oil resulting from thedistillation of crude petroleum and its fractions over caustic, andneutralized acid oils resulting from treatment of lubricating oil withsulfuric acid containing an alkali metal salt of an organic acidselected from the group consisting of naphthenic and sulfonic acids andabout 25% by volume of Water, agitating vigorously said Water-containingadmixture to emulsify same, extracting the emulsified admixture withliquefied propane in an amount in the range from about 2 volumes toabout 10 volumes per volume of hydrocarbon oil at a temperature in therange between 100 and 200 F. to form an oil phase, an intermediate phaseand an aqueous phase, separating and recovering said oil phase and saidaqueous phase, removing propane from said oil phase and recovering anoil substantially free of salt of said organic acid.

8. A process for producing a hydrocarbon substantially free of salts ofan organic acid which comprises forming a mixture of a hydrocarbon oilselected from the group consisting of neutralized slop oils, neutralizedsludges resulting from treatment of lubricating oil fractions in propanesolution with sulfuric acid, neutralized bottoms fractions from thedistillation of naphtha, oil resulting from the distillation of crudepetroleum and its fractions over caustic, and neutralized acid oilsresulting from treatment of lubricating oil with sulfuric acidcontaining sodium naphthenate and sodium sulfonate and about 25% byvolume of water, agitating vigorously said water-containing admixture toeinulsify same, extracting the emulsified admixture with 4 volumes ofliquefied propane per volume of hydrocarbon oil at a temperature aboutF. to form an oil phase, an intermediate phase and an aqueous phase,separating and recovering said oil phase and said aqueous phase,removing propane from said oil phase and recovering an oil substantiallyfree of sodium naphthenate and sodium sulfonate.

9. A process for producing a hydrocarbon oil substantially free of saltsof an organic acid which comprises forming an admixture of an oilselected from the group consisting of neutralized slop oils, neutralizedsludges resulting from treatment of lubricating oil fractions in propanesolution with sulfuric acid, neutralized bottoms fractions from thedistillation of naphtha, oil resulting from the distillation of crudepetroleum and its fractions over caustic, and neutralized acid oilsresulting from treatment of lubricating oil with sulfuric acidcontaining an alkali metal salt of an organic acid selected from thegroup consisting of naphthenic and sulfonic acids and about 25% byvolume of water, agitating vigorously said water-containing admixture toemulsify same, extracting the emulsified admixture with about 4 volumesof propane per volume of hydrocarbon oil at a temperature of about 150F. to form an oil-propane admixture, washing the oil-propane admixturewith further quantities of water, settling the Washed oil-propaneadmixture to form an oil phase, an intermediate phase, and an aqueousphase, separating and recovering said oil phase and said aqueous phase,removing propane from said oil phase, and recovering an oilsubstantially free of salts of said organic acids.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,235,639 Koch Mar. 18, 1941 2,301,335 Showalter et al. Nov.10, 1942 2,406,748 Dickinson Sept. 3, 1946 2,413,310 Bloch Dec. 31, 19462,446,040 Blair July 27, 1948

9. A PROCESS FOR PRODUCING A HYDROCARBON OIL SUBSTANTIALLY FREE OF SALTSOF AN ORGANIC ACID WHICH COMPRISES FORMING AN ADMIXTURE OF AN OILSELECTED FROM THE GROUP CONSISTING OF NEUTRALIZED SLOP SOILS, NEUTALIZEDSLUDGES RESULTING FROM TREATMENT OF LUBRICATING OIL FRACTIONS IN PROPANESOLUTION WITH SULFURIC ACID, NEUTRALIZED BOTTOMS FRACTIONS FROM THEDISTILLATION OF NAPHTHA, OIL RESULTING FROM THE DISTILLATION OF CRUDEPETROLEUM AND ITS FRACTIONS OVER CAUSTIC, AND NEUTRALIZED ACID OILSRESULTING FROM TREATMENT OF LUBRICATING OIL WITH SULFURIC ACIDCONTAINING AN ALKALI METAL SALT OF AN ORGANIC ACID SELECTED FROM THEGROUP CONSISTING OF NAPHTHENIC AND SULFONIC ACIDS AND ABOUT 25% BYVOLUME OF WATER, AGITATING VIGOROUSLY SAID WATER-CONTAINING ADMIXTURE TOEMULSIFY SAME, EXTRACTING THE EMULSIFIED ADMIXTURE WITH ABOUT 4 VOLUMESOF PROPANE PER VOLUME OF HYDROCARBON OIL AT A TEMPERATURE OF ABOUT 150*F. TO FORM AN OIL-PROPANE ADMIXTURE, WASHING THE OIL-PROPANE ADMIXTUREWITH FURTHER QUANTITIES OF WATER, SETTLING THE WASHED OIL-PROPANEADMIXTURE TO FORM AN OIL PHASE, AN INTERMEDIATE PHASE, AND AN AQUEOUSPHASE, SEPARATING AND RECOVERING SAID OIL PHASE AND SAID AQUEOUS PHASE,REMOVING PROPANE FROM SAID OIL PHASE, AND RECOVERING AN OILSUBSTANTIALLY FREE OF SALTS OF SAID ORGANIC ACIDS.